Since 2007, al Shabab, an al Qaeda-linked militia, has been locked in a violent stalemate with Somalia's weak and dysfunctional Transitional Federal Government (TFG). Back in 2009, it was clear that this conflict was far from inevitable: today's tragedy is a result of a series of bad policy decisions by the United States, regional actors, and the United Nations. And it has been actively sustained by external forces -- al Qaeda provided al Shabab funding and tactical expertise while the United States and other countries bolstered the TGF, fueling an unproductive conflict. Somalis in Mogadishu have sometimes characterized the bloody saga as a "diaspora war," as both sides are at least partially proxies for foreign powers.

Until this summer, al Shabab fought unsuccessfully to rout the TFG from its strongholds in the presidential palace and ports, and the TFG was unable to reliably project its authority beyond a nominal presence in some of Mogadishu's neighborhoods. Al Shabab's human rights abuses and the peacekeepers' regular, indiscriminate mortar fire were brutal burdens for Mogadishu's residents. Hundreds of thousands fled their homes to other parts of Somalia, to Kenya and Yemen, and onward into the Middle East. The conflict devastated the Somali economy, drained the country's resources, weakened its population, and set the stage for the terrible famine that is obliterating the southern half of the country.

The impasse seemed more or less unbridgeable until the first week of August, when al Shabab forces shouldered their weapons and walked, unexpectedly, out of Mogadishu. A little less than a year before, African Union peacekeepers (known by their acronym, AMISOM) had managed to eke out some territorial gains after al Shabab's September 2010 so-called Ramadan Offensive ended in failure. When al Shabab withdrew, the AU claimed the retreat as a hard-earned victory but was quick to warn that the move would probably be temporary and tactical -- a sign that al Shabab was planning to return to the hit-and-run guerrilla tactics it had used to drive some 17,000 Ethiopian troops (